Exploring conjugate heat transfer in Bingham fluid flow: A 3D computational approach incorporating double diffusion and the Papanastasiou model

In this study, double diffusion and conjugate heat transfer are adopted to examine the factors affecting the heat and mass transfer on the performance and durability of many electronic devices such as light-emitting diode (LED). The non-linear rheology of Bingham fluid, utilizing the Papanastasiou model to manage yield stress discontinuities, is investigated inside a cubical enclosure. A solid vertical plate with slab fins is considered to be heated externally, playing the role of an LED base plate. A collection of non-linear differential equations simulates the physical phenomenon. A promising tool, the finite element scheme is utilized for computations which is first validated with experimental and numerical data. Optimization of computational cast reveals that three-dimensional (3D) result depicts the best structural visualization but it is much more costly than two-dimensional (2D). The non-Newtonian behaviour shows that heat and mass fluxes decrease with yield number (y_t) and the maximum is obtained in the case of Newtonian materials. The thermal energy transport increases with both thermal conductivity ratio (R_k) and plate thickness (x_p). Increasing the Rayleigh number (Ra) increases the shear rate and unyielded region diminishes near the fins, leading to promoted convection. It is noticed that Soret (S_r) and Dufour (D_f) parameters have positive impacts on heat and mass transfer rates. Results show that mass flow rate rises with Lewis number (Le) while the opposite trend is seen in heat transmission. The influence of Ha reveals that heat and mass transfer rates are maximum in the absence of magnetic fields. The relative change of mean Nusselt number (Nu_avg) is low at the beginning and rises with Ha, attens the maximum decrease at Ha = 60.